Estimation of General Combining, and Genetic Parameters in Maize (Zea mays L.) by Using Line x Tester Crosses

Abstract

This study was conducted in the fields of a farmer in the city of Ramadi - Anbar Governorate - Iraq, during the spring and fall seasons of (2020), where the seeds of eight pure lines of maize were planted (NadH26, Zm.69, Sy.52, Inb. 23, Am.63, NadH.52, MGW-16, Zm.6). Then the lines hybridized with each other by the method (Line x Tester) to produce 15 hybrids. Parental seed and individual hybrids planted in the fall season (2020) were compared according to the R.C.B.D with three replications, for the purpose of estimating the effects of combining ability of lines, hybrids, some genetic parameters and Hybridization for studied traits are: Number of days from planting to 50% to Silking, leaf area, dry plant weight, number of rows, number of grains per row, weight of 300 grains and plant yield. The results of the study showed significant differences between parents and their hybrids for all the studied traits, Tester (Zm.69) was superior by showing the highest effect of general combining in the desired direction for most of the traits, while the line (Am.63) showed the highest effect of general combining with the positive direction of most of the studied traits. The hybrid (Zm.69 X Zm.6) gave the highest effect of specific combining ability of the weight 300-grain and the plant yield was 3.65 and 44.15, respectively. The ratio between the variance of general and specific combining ability was less than one for most of the traits, and the dominance variance was large than the additive variance for most of the traits. The heritability broad sense was high for most of the studied traits, while the heritability narrow sense was low for all traits except for the two traits of leaf area and dry weight of the plant, and degree of dominance was large than one for most of the traits, which indicates the control of the genes of super-dominance over the inheritance of these traits. The expected genetic advance is low for all traits. The results also showed that the hybrid ( MGW-16 X Sy.52) gave the highest positive hybrid compared to the best parents for the characteristics of the number of rows in ear, the number of grains per row, and plant yield, which reached (17.78%, 7.18% and 24.24%) respectively. It is concluded from this study the possibility of using some of the superior parents in their to derive individual hybrids with a specific combining ability for the production of high yield as most of their traits were under the influence of genes of superior dominance.